Abstract: The ore-forming material source and genesis of Jiajiapuzi banded iron formation(BIF) in Benxi City are studied by the geochemical analysis of combining major and rare earth elements (REE). The results show that the main chemical compositions of Jiajiapuzi BIF are TFe₂O₃ and SiO₂, with low content of Al₂O₃ and TiO₂, which is basically the same characteristics as the BIFs in Anshan-Benxi area, Wutai Mountain in Shanxi Province and Qian'an area in eastern Hebei Province, indicating that the BIF is a kind of chemical sedimentary rock with a little clastic material. The REEs are characterized by weak deficiency of LREEs, enrichment of HREEs and obvious positive Eu anomaly, reflecting the REEs in BIF are from a mixture of volcanic hydrothermal fluid and seawater. The Jiajiapuzi BIF genetically belongs to Algoma-type.